Information recording medium, apparatus and method for recording or reproducing data thereof

ABSTRACT

An information recording medium suitable for optical discs such as DVD-RAM is provided for integrated management of data as objects in different kinds of AV formats. Also apparatus is provided for data recording and playing to the medium. The medium stores management information including program chain information (PGC information) defining the playback order of the objects, and object information containing information relevant to the objects. The object information has general information of the object, attribute information and a map associating a playback time point of the object with an address on the optical disc of a component of the object to be played. The PGC information has cell information including information about type of object, identification information. The order of the cell information in the PGC information corresponds to the order in which the objects are played back.

[0001] This application is based on application No. 10-289089 filed inJapan, the contents of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to readable/writable informationrecording medium. More specifically, the present invention relates to aninformation recording medium for recording multimedia data in differentkinds of formats such as movie image data, still picture data and audiodata; and a data recording apparatus and replaying apparatus for themedium.

[0004] 2. Related Art

[0005] Development of phase change type disc DVD-RAM has increasedrecording capacity of a rewritable optical disc from about 650 MB to afew GB. The DVD-RAM is now expected to become a medium not only forcomputers but also a recording/playing medium for audio/video(hereinafter abbreviated as AV) technologies in combination withstandardization of a digital AV data coding technique called MPEG(MPEG2). Specifically, the DVD-RAM is expected to replace magnetic tapewhich has been a major AV recording medium.

[0006] (DVD-RAM)

[0007] Advancement in high-density recording technology for rewritableoptical discs in recent years has made it possible to store not onlycomputer data and audio data but also image data as well.

[0008] Conventionally, land and groove are formed on a signal recordingsurface of the optical disc.

[0009] Signals used to be recorded only on the land portion or in thegroove portion. Later, land-group recording method was developed forrecording signals both in the land portion and in the groove portion,practically doubling the recording density. For example, a techniquedisclosed in Japanese Patent Laid-Open Publication No. 8-7282 is wellknown.

[0010] Another of such techniques is CLV (Constant Linear Velocityrecording) method for improving recording density. From this technique,zone CLV method was developed and is now commercially practiced forsimplified control in application. Japanese Patent Laid-Open PublicationNo. 7-93873 is a known example of this technique.

[0011] With such development in the optical disc for greater recordingcapacity, a technological challenge is how to record AV data includingimage data, thereby achieving new performances and functions that havenever been realized by prior art AV apparatuses.

[0012] The development of the large-capacity rewritable optical disc isexpected to replace the conventional tape medium for recording/playingAV data. The change from tape to disc will bring substantial changes inthe function and performance of the AV equipment.

[0013] The biggest change to be brought by the disc is tremendousimprovement in random access capability. If tape is to be accessedrandomly, rewinding time of the tape, which is usually a few minutes perreel, must be taken into account. Such an access time is extremelyslower than a seek time (which is shorter than a few tens ofmillisecond.) for the optical disc. Thus, in a practical sense, the tapecannot be a random access medium.

[0014] Such a superb random access capability of the optical disc canrealize distributed recording of AV data in the optical disc, which wasnot possible with the conventional tape medium.

[0015] Referring now to the attached drawings, FIG. 1 is a block diagramof a DVD recorder drive unit. The drive unit comprises an optical pickup11 for reading data stored in a DVD-RAM disc 100, an ECC (ErrorCorrecting Code) processor 12, a one-track buffer 13, a switch 14 forselecting between input and output to and from the track buffer 13, anencoder 15, and a decoder 16.

[0016] As shown in the figure, the DVD-RAM disc 100 uses one sector (1sector=2 KB) as a smallest unit of data recording, and one ECC block (1ECC block=16 sectors) is used as a unit for error correcting operationperformed by the ECC processor 12.

[0017] The track buffer 13 is a buffer for storing AV data at a variablebit rate to record AV data effectively in the DVD-RAM disc 100.Specifically, reading/writing for the DVD-RAM 100 is performed at afixed rate (Va), whereas the bit rate (Vb) of AV data is variedaccording to complexity of contents (e.g. an image for video data). Thebuffer 13 absorbs difference between these two bit rates. When the AVdata have a fixed bit rate such as in a video CD, then the track buffer13 is not required.

[0018] If this track buffer 13 is used more effectively, distributedrecording of AV data on the disc 100 becomes possible. This will bedescribed more specifically here below, referring to FIGS. 2A and 2B.

[0019]FIG. 2A is a diagram showing address space on the disc. Accordingto FIG. 2A, AV data is stored in a distributed manner, i.e. in acontinuous area [a1, a2] and in another continuous area [a3, a4]. Insuch a case, the AV data can be replayed continuously supplying datastored in the buffer 13 to the decoder portion 16 while seek is beingmade from point a2 to point a3. This situation is shown in FIG. 2B.

[0020] The AV data starting from the location a1 are read, and thenentered to the track buffer 13 from time t1, upon which time the trackbuffer 13 begins to output the data. Thus, the buffer 13 accumulatesdata at a rate equal to the difference (Va−Vb) between the input rate(Va) to the buffer 13 and the output rate (Vb) from the buffer 13. Thissituation continues until the retrieval reaches a2 represented by a timepoint t2, by which time the amount of data in the buffer 13 hasaccumulated to amount B(t2). From time t2 to time t3, until the datapickup operation is resumed from the area starting at a3, the amount ofdata B(t2) stored in the track buffer 13 is being consumed in order tokeep the decoder 16 supplied with data.

[0021] In other words, when the amount of data ([a1, a2]) read beforethe seeking is greater than a certain volume, then the AV data can becontinuously supplied without being interrupted by the seek.

[0022] The above description is for reading of data from the DVD-RAM,i.e. for a play back operation. The same goes with writing data to theDVD-RAM, i.e. for a recording operation.

[0023] As described above, with the DVD-RAM, continuousreplaying/recording is possible even if AV data is stored in thedistributed manner, as long as the amount of data on each continuousrecord is greater than a certain volume.

[0024] In order to enhance advantages of the large-capacity recordingmedium, i.e. DVD-RAM, a UDF (Universal Disc Format) file system is usedin the DVD-RAM as shown in FIG. 3 to allow access to the disc by using aPC. UDF information is recorded in “Volume” area of the diagram. Detailsof the UDF file system is disclosed in the “Universal Disc FormatStandard.”

[0025] (Prior-Art AV Equipment)

[0026] Next, description will be made for prior art AV equipmentcommonly used by many users.

[0027]FIG. 4 is a diagram showing relationships among conventional AVequipment, media and formats. For example, if a user wants to watch avideo program, a videocassette must be loaded into a VTR, and theprogram must be viewed using a TV set. If the user wants to listen tomusic, then a CD must be loaded into a CD player or CD radio-cassetteplayer, and the program must be listened through a speaker system orthrough headphones. Specifically, according to the conventional AVsystem, each format (video or audio) is paired with a correspondingmedium, respectively.

[0028] For this reason, each time when listening or watching a program,the user must select an appropriate medium and change one to another AVequipment appropriate to the medium. This is inconvenient from theuser's viewpoint.

[0029] (Digitization)

[0030] Meanwhile, along with recent popularization of digitaltechnology, a DVD videodisc was introduced as package software, whereassatellite digital broadcast was introduced in the broadcasting industry.These developments are backed by digital technology innovation,especially by MPEG as an internationally accepted standard.

[0031]FIG. 5 is a diagram showing MPEG streams used in the DVD videodiscand the satellite digital broadcast mentioned above. The MPEG standardhas a hierarchy structure as shown in FIG. 5. An important point to notehere is that the MPEG stream eventually used by an application in thepackage medium such as the DVD videodisc is different from the MPEGstream in the communication medium such as the satellite digitalbroadcasting. The former is called “MPEG program stream”, in which datatransfer is made by the unit of pack, reflecting the size of a sector(2048 bytes in DVD video disc) as the unit of recording in the packagesoftware. On the other hand, the latter is called “MPEG transportstream”, in which the unit of data transfer is a TS packet having a sizeof 188 bytes, reflecting the application to ATM (Asynchronous TransferMode) systems.

[0032] The MPEG is expected to eliminate borders between different AVmedia, as a universal coding technology of image signals and digitaldata. However, because of such small differences as described above,there is not yet any AV equipment or media capable of handling both thepackage media and communication media.

[0033] (Changes Brought by DVD-RAM)

[0034] Introduction of the large capacity DVD-RAM is a step forward toelimination of the inconvenience that users feel in conventional AVequipment. As described earlier, the DVD-RAM incorporated with the UFDfile system is accessible from the PC. By using different pieces ofapplication software on the PC, it is now possible to play varieties ofcontents such as video, still picture and audio programs on a singlepiece of equipment, i.e. the PC.

[0035] As shown in FIG. 6, the user can move a cursor with a mouse ontoa file displayed on a screen, and then double-click (or single-click) toreplay contents of the file such as a movie displayed in left-top areaof the screen.

[0036] Such a convenience becomes possible by combination of flexibilityoffered by the PC and large storage capacity offered by the DVD-RAM.

[0037] Backed by increasing popularity of the PC in recent years anumber of different AV data can now be handled fairly simply on the PCas shown in FIG. 6. However, even though number of PC users is expectedto increase, the popularity and easiness of operation of the PC are notso high and simple as those of the home TV or home video systems.

[0038] It is therefore an object of the present invention to solve thefollowing problems identified as hurdles to optimum performance of theoptical discs such as the DVD-RAM, as an AV recording medium of the nextgeneration.

[0039] A world to be realized by the DVD recorder would be a world inwhich the user can freely handle different formats and contents withoutcaring about the differences, by using a single medium on a single pieceof AV equipment as shown in FIG. 7.

[0040]FIG. 8 shows an example of a menu used in the DVD recorder.According to this menu, the user can select from 1) “The Foreign MovieTheater” recorded from satellite digital broadcasting, 2) “The MorningDrama Series”, 3) “The World Cup Finals” each recorded from conventionalterrestrial broadcasting, and 4) a Beethoven dubbed from a CD, on a TVscreen without caring about the original medium or the recording format.

[0041] The biggest problem in developing such a DVD recorder as above ishow to manage uniformly the AV data and streams of many differentformats.

[0042] No special managing method will be necessary if only a limitednumber of existing formats are to be handled. However, a managing methodcapable of handling not only a number of existing formats but also newformats to be introduced in the future has to be developed in order torealize the above-mentioned world of DVD recorder.

[0043] Even so, certain difference between a future user interface andthose incorporated in the capability of uniformly handling the differentAV streams may create a certain level of inconvenience similar to theinconvenience described for the prior-art. Specifically, the user mayhave to perform different operation depending upon the contents orformat.

SAMMARY OF THE INVENTION

[0044] The present invention is made to solve the above problem, and itis therefore an object of the present invention to provide aninformation recording medium capable of uniformly handling differentkinds of AV streams, and to provide a recording apparatus and a playingapparatus for said information recording medium.

[0045] In a first aspect of the invention, an information recordingmedium is provided for recording objects which include at least one ofimage data and audio data. The recording medium stores objectinformation and playback control information.

[0046] The object information includes identification information andmap information for each object. The identification informationidentifies the object. The map information associates a playback time ofthe object with a logical address (or address on a disc) of a componentof the object on the medium. The component is played back at theplayback time.

[0047] The playback control information includes at least one of cellinformation in a predetermined order. The cell information contains typeinformation, identification information and playback sectioninformation. The type information indicates a kind of the object. Theidentification information identifies the object. The playback sectioninformation specifies a section in which the object is being played.

[0048] The order of cell information in the playback control informationindicates the order in which the objects specified by respective cellinformation are played.

[0049] In a second aspect of the invention, an apparatus for recordingdata to the information recording medium comprises a unit for receivingan MPEG transport stream from external equipment, a unit for reading the“random_access_indicator” from the received MPEG transport stream and aunit for generating an access point information based on the read“random_access_indicator”.

[0050] In a third aspect of the invention, an apparatus for recordingdata to the information recording medium comprises a unit for recordingtype information and the type information indicating a kind of object tothe playback section information.

[0051] In a forth aspect of the invention, an apparatus for reading datafrom the information recording medium comprises a pickup unit forreading data of the object recorded in the recording medium, a pluralityof decoding units for decoding the data of the object according to thekind of the object, a selecting unit for selecting one of the decodingunits for playback operation and a controlling unit for reading the typeinformation of the object specified in the object information, andcontrolling the selecting units to select one of the decoding unitsaccording to the read type information.

[0052] In a fifth aspect of the invention, a method for recording datato the information recording medium comprises the steps of receiving anMPEG transport stream from external equipment, reading the“random_access_indicator” from the received MPEG transport stream andgenerating an access point information based on the read“random_access_indicator”.

[0053] In a sixth aspect of the invention, a method for reproducing datafrom the information recording medium, comprises the steps of readingout object data from the recording medium, reading out the typeinformation of the playback control information in the recording medium,and decoding the read object data according to the read typeinformation.

[0054] The recording medium according to the present invention makespossible not only to record but also to integrally manage different AVformats on the same disc, thereby making possible to manage a variety ofobjects each recorded in a different format on one recording medium.

[0055] The apparatus and method for recording according to the presentinvention makes possible to create and record the type information forindicating the kind of objects to be recorded, thereby making possibleto embody the above optical disc compatible to the variety of AVformats.

[0056] The apparatus and method for reproducing according to the presentinvention makes possible to decode data of read object in the externalequipment even if the playing apparatus does not have the capability todecode the data of the read object.

BRIEF DESCRIPTION OF THE DRAWINGS

[0057]FIG. 1 is a block diagram of a drive unit of a DVD recorder.

[0058]FIG. 2A is a diagram showing address space on a disc.

[0059]FIG. 2B is a diagram showing data accumulation in a track buffer.

[0060]FIG. 3 is a diagram showing a file structure through a filesystem.

[0061]FIG. 4 is a diagram showing relationships among different kinds ofprior art AV equipment and corresponding media.

[0062]FIG. 5 is a diagram showing an MPEG program stream and an MPEGtransport stream.

[0063]FIG. 6 is an illustration of a PC screen when an AV data file isbeing accessed on the PC.

[0064]FIG. 7 is a diagram showing relationships to be created by a DVDrecorder among different kinds of AV equipment.

[0065]FIG. 8 is an example of a selection menu given by the DVDrecorder.

[0066]FIG. 9A is a diagram showing relationships between an AV file anda directory on the computer readable DVD-RAM disc.

[0067]FIG. 9B is a diagram showing address space on the disc.

[0068]FIG. 10 is a diagram showing relationships among an object, objectinformation and PGC information.

[0069]FIG. 11 is a diagram showing management information derived fromthe object information for each stream.

[0070]FIG. 12 is a diagram showing relationships among a movie object(M_VOB), movie object information (M_VOBI), and PGC information (PGCI).

[0071]FIGS. 13A, 13B, 13C, 13D, 13E and 13F are diagrams describing atime map according to the present invention.

[0072]FIGS. 14A, 14B, 14C and 14D are diagrams each of which shows eachstage of the MPEG transport stream.

[0073]FIG. 15 is a diagram showing relationships between an audio object(AOB), audio object information (AOBI) and PGC information (PGCI).

[0074]FIG. 16 is a diagram showing relationships among a still pictureobject (S_VOBS), still picture object information (S_VOBS), and PGCinformation (PGCI).

[0075]FIG. 17 is a diagram describing management information in aDVD-RAM.

[0076]FIG. 18 is a block diagram of a player model according to thepresent invention.

[0077]FIG. 19 is a block diagram of the DVD recorder according to thepresent invention.

[0078]FIG. 20 is a Block diagram of a DVD player or a data reproducingapparatus according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] With reference to the accompanying drawings, detailed descriptionwill be made for a DVD-RAM, a DVD recorder, and a DVD player aspreferred embodiments of the present invention.

[0080] (Logic Structure of Data on DVD-RAM)

[0081] The DVD-RAM according to the present invention makes possible torecord and manage integrally AV data and AV streams of many differentkinds of formats on a single disc. This allows it to record on a singledisc AV streams of different formats including a terrestrialbroadcasting TV program, a digital broadcasting TV program transmittedin the MPEG transport stream format, a video stream taken by a digitalvideo camera, a still picture taken by a digital still camera, and videodata coded in the MPEG program stream, and so on. Further, the datarecorded in the DVD-RAM can be played in a given sequence. For thispurpose, the DVD-RAM according to the present invention is provided withmanagement information for managing the AV streams without depending onthe types of format of the AV data or AV streams.

[0082] First, structure of the data recorded in the DVD-RAM according tothe present invention is described with reference to FIGS. 9A and 9B. Adiagram in FIG. 9A is a data structure of a DVD-RAM disc 100, which canbe seen by a file system. FIG. 9B shows a structure of a physical sectorin the disc 100.

[0083] As shown in the figure, a first portion of the physical sector isa lead-in area 31 which stores therein standard signals necessary forstabilizing servo mechanism, identification signals for differentiatingfrom other media, and so on. The lead-in area 31 is followed by a dataarea 33 which stores logically available data. A last portion is alead-out area 35 storing signals similar to those in the lead-in area31.

[0084] A front portion of the data area 33 stores with volumeinformation which is management information for the file system. Sincethe file system is a known technique, no details will be describedherein.

[0085] The file system allows the data in the disc 100 to be handled asdirectories and files as shown in FIG. 9A. As understood from FIG. 9A,all the data handled by the DVD recorder is managed under VIDEO_RTdirectory immediately below the ROOT directory.

[0086] The DVD recorder according to the present embodiment handles twokinds of files, i.e. AV files containing audio-video data (AV data), andmanagement information files containing information for managing the AVfiles. According to the example shown in FIG. 9A, the managementinformation file is identified as “VIDEO_RT. IFO”, whereas the AV filesinclude a file “M_VOB.VOB” which contains movie data, “D_VOB.VOB” whichcontains image data from digital broadcasting, “AOB. AOB” which containsaudio data, and so on. Each of these files will be detailed here below.

[0087] It should be noted here that according to the present embodiment,each AV stream is defined as an object (“Object”). Specifically, theobjects may include a variety of AV streams such as MPEG program stream,MPEG transport stream, audio stream, still picture data, and so on. Eachof these AV streams is abstracted as the object so that the managementinformation of these AV streams can be defined as object information(Object I) of a universal format.

[0088] (Management Information)

[0089] First, the management information will be described referring toFIG. 10. The management information has object information 80 formanagement of recording locations of the object and attribute thereof,and program chain information (PGC information) 50 and 70 which defineplayback sequence, playback time and so on for data to be played backfrom the DVD-RAM.

[0090] The above-described abstraction is possible for the AV streamsbecause the AV streams have time attribute and other elements in common,although each of the different formats has certain differences from theothers. AV streams having a common format are stored in a same AV filein the order of recording.

[0091] The object information (Object I) 80 includes general informationabout the object (Object GI) 80 a, attribute information of the object(Attribute I) 80 b, and an access map 80 c for converting the objectplayback time into addresses on the disc.

[0092] The access map 80 c is necessary because the AV stream generallyhas two standards, i.e. a time domain and a data (binary digit string)domain, which do not have perfect correlation with each other. Forexample, in a video stream coded by MPEG-2 video which is now aninternational standard of the video stream, use of variable bit rate (amethod in which the bit rate is changed depending on the level ofcomplexity of an image) is becoming a mainstream. According to thismethod, there is no proportional relationship between the amount of datafrom the beginning and the accumulated length of playback time, andtherefore random accessing cannot be performed based on the time axis.In order to solve this problem, the object information 80 has the accessmap 80 c for conversion between the time axis and the data (binary digitstring) axis. As will be described later, one object comprises aplurality of object units (VOBU), and therefore the access map 80 c hasdata that correlates or associates the time region with the addressregion for each of the object units.

[0093] The PGC information 50, 70 are the information for controllingthe playback of the object, i.e. image data and audio data. The PGCinformation 50, 70 represent a unit of data to be played back when theDVD player plays continuously data back. Specifically, each of the PGCinformation 50, 70 indicates an object to be replayed, and a playbacksequence of cells 60, 61, 62 and 63. Each of cells 60, 61, 62 and 63indicates any playback section of this particular object. The cells 60,61 . . . will be described later in more detail. Thee PGC informationcomprises two kinds of information comprising an original PGCinformation 50 and a user defined PGC information 70. The original PGCinformation 50 is automatically generated by the DVD recorder uponrecording the object so that all of the recorded objects are included.On the other hand, with the user-defined PGC information 70, the usercan freely define the playback sequence. The PGC information 50 and 70have the same structure and function differing only in that theuser-defined PGC information 70 is defined by the user. Thus,description in further detail will be made only for the original PGCinformation 50.

[0094] As shown in FIG. 10, the original PGC information 50 includes atlease one of the cell information. The cell information 60 . . .specifies an object to be replayed, and a replay section of the object.Generally, the PGC information 50 records a plurality of cells in acertain sequence. This recording sequence of the cell information in thePGC information 50 indicates the sequence in which the objects specifiedin respective cells are replayed.

[0095] Each cell, the cell 60 for example, includes type information(“Type”) 60 a which indicates the kind of object specified, an objectidentification (Object ID) 60 b which identifies the object, startingposition information (“Start”) 60 c on the time axis of the object, andending position information (“End”) 60 e oh the time axis in the object.

[0096] When the data is replayed, the cell information 60 in the PGCinformation 50 is read out successively, so that the object specified bythe cell is replayed by successively playing portions of the objectrepresented by the playback sections specified by respective cells.

[0097] (Subclasses of the Object Information)

[0098] In order for the abstracted object information to be applied toan actual AV stream, a concretization must be provided. This principlemay be understood easily as the class concept employed in anobject-oriented model. More specifically, understanding will becomeeasier if the object information is considered as a super-class, andmore concrete structures created for each of the AV streams areconsidered as subclasses. FIG. 11 shows these concretized subclasses.

[0099] According to the present embodiment, as shown in FIG. 11, theobject information has subclasses defined as a movie subclass, a stillpicture subclass, an audio subclass, and a digital broadcast subclass.Specifically, following subclasses are defined as concrete information:Movie object information (M_VOBI) is defined as the object informationfor video data (in MPEG program stream). Digital video objectinformation (D_VOBI) is defined as the object information for digitalbroadcasting (in MPEG transport stream). Audio object information (AOBI)is defined as the object information for audio, and still picture videoobject information (S_VOBI) is defined as the object information forstill pictures. Each of the above will be described here below.

[0100] The movie object information 82 includes MPEG program streamgeneral information (M_VOB_GI) 82 a, movie object stream information(M_VOB_STI) 82 b, and a T map 82 c.

[0101] The general information (M_VOB_GI) 82 a includes movie objectIdentification information (M_VOB_ID), movie object recording time(M_VOB_REC_TM), movie object starting time information (M VOB_V_S_PTM),and movie object ending time information (M_VOB_V_E PTM).

[0102] The movie object stream information (M_VOB_STI) 82 b includesvideo stream information (V_ATR) having coding attributes of the videostream, the number of audio streams (AST_Ns), and audio streaminformation (A_ATR) having coding attributes of the audio stream.

[0103] The T map 82 c includes a leading address of the movie object inthe AV file, playback time (VOBU_PB_TM) and data size (VOBU_SZ) of eachof the movie object units (VOBU). The movie object unit (VOBU) is thesmallest unit to be accessed in the movie object (M_VOB), and will bedetailed later.

[0104] The digital broadcast object information (D_VOBI) 86 includesMPEG transport stream general information (D_VOB_GI) 86 a, streaminformation (D_VOB_STI) 86 b, and a T map 86 c.

[0105] The general information of the digital broadcasting object(D_VOB_GI) 86 a includes digital broadcasting object identificationinformation (D_VOB_ID), digital broadcasting object recording time(D_VOB_REC_TM), digital broadcasting object starting time information(D_VOB_V_S_PTM), and digital broadcasting object ending time information(D_VOB_V_E PTM).

[0106] The digital video object stream information (D_VOB_STI) includesinformation (PROVIDER_INF) which contains additional informationprovided in the digital broadcasting. The T map 86 c includes a leadingaddress of the digital broadcasting object (D_VOB) in the AV file,playback time (VOBU_PB_TM) and data size (VOBU_SZ) for each object unit(VOBU).

[0107] The audio object information (AOBI) 88 includes audio streamgeneral information (AOB_GI) 88 a, stream information (AOB_STI) 88 b,and a T map 88 c. The audio stream general information (AOB_GI) 88 aincludes audio object identification information (AOB_ID), audio objectrecording time (AOB_REC_TM), audio object starting time information(AOB_S_TM), and audio object ending time information (AOB_E_TM). The AOBstream information (AOB_STI) 88 b includes audio stream information(A_ATR) having coding attributes of the audio stream. The T map 88 cincludes a leading address of the audio object in the AV file, playbacktime (AOBU_PB_TM) and data size (AOBU_SZ) for each audio object unit(AOBU). The audio object unit (AOBU) is the smallest access unit in theaudio object (AOB), and will be detailed later.

[0108] Still picture object information (S_VOBSI) 84 includes stillpicture general information (S_VOBS_GI) 84 a, still picture streaminformation (S_VOBS_STI) 84 b, and an S map 84 c. The still picturegeneral information (S_VOBS_GI) 84 a includes still picture objectidentification information (S_VOBS_ID), still picture object recordingtime (S_VOBS_REC_TM), still picture object starting picture number(SVOBS_S_NO), and still picture object ending picture number(SVOBS_E_NO). The still picture stream information (S_VOBS_STI) 84 bincludes still picture attribute information (V_ATR) having informationabout a compression format of the still picture object. The S map 84 cincludes a leading address of still picture object (S_VOBS) in the AVfile, and data size (S_VOB_SZ) for each still picture.

[0109] As described above, a stream information table corresponding toeach type of AV stream can be defined as shown in FIG. 11 by putting theabstracted object information into a more concrete data.

[0110] (Correspondence Between Object Information and Cell Information)

[0111] Referring next to FIG. 12, the movie object information (M_MOBI),which is one of the concrete forms of the object information (Object I),is taken as an example to see correspondence with the cell information.

[0112] When the type information (Type) specified in the cellinformation has the value “M_VOB”, this cell corresponds to a movieobject. Likewise, when the type information has the value “D_VOB”, thenthe cell corresponds to a digital broadcasting object, and when the typeinformation has the value “AOB”, then the cell corresponds to an audioobject.

[0113] Based on the object ID (Object ID), the object information (VOBI)corresponding to the ID can be found. The object ID has a one-to-onecorrespondence to the movie object ID (M_VOB_ID) contained in thegeneral information (M_VOB_GI) of the movie object information(M_VOB_I).

[0114] As described above, the object information corresponding to thecell information can be retrieved by using the type information (Type)and the object ID (Object ID).

[0115] The starting position information (Start) in the cell informationcorresponds to the start time information (M_VOB_V_S_PTM) of the movieobject information. When the two values indicate a same time, itindicates that the cell is the first portion to be played of the movieobject. On the other hand, when the starting position information(Start) has a value greater than that of the start time information(M_VOB_V_S_PTM), it indicates that the cell is to be played as a middleportion of the movie object. In such a case, the playback of the cell isdelayed from the top of the object by the difference (time difference)between the start time information (M_VOB_V_S_PTM) and the startingposition information (Start). The same relationship exists between thecell ending position information (End) and the end time information(M_VOB_V_E_PTM) of the movie object.

[0116] As described above, playback starting and the ending of a givencell can be obtained as relative points of time within the object byusing the starting information (Start) and the ending informationrespectively in the cell information, and the start time information(M_VOB_V_S_PTM) and end time information (M_VOB_V_E_PTM) respectively inthe general information (M_VOB_GI) of the movie object information(M_VOBI).

[0117] The T map of the movie object is a table comprising a playbacktime and data size for each movie object unit (VOBU). By using the Tmap, the relative playback start time and the relative playback end timeof a given cell within the movie object described above can be convertedto address data.

[0118] Now, the address conversion using the T map mentioned above willbe specifically described with reference to FIGS. 13A, 13B, 13C, 13D,13E and 13F.

[0119]FIG. 13A shows movie objects (M VOB) representing video display onthe time axis. FIG. 13B shows the time map comprising the length ofplayback time and the data size for each movie object unit (VOBU). FIG.13C shows the movie object expressed on the data (sector series) axis.FIG. 13D shows pack series as an enlarged portion of the movie object.FIG. 13E shows a video stream. FIG. 13F shows an audio stream.

[0120] The movie object (M_VOB) is an MPEG program stream. In MPEGprogram stream, a video stream and an audio stream are assembled into apacket (PES packet), and a plurality of the packets (PES packets) arepacked into a sequence. In the example, one pack contains one packet(PES packet), and a pack is allocated with one sector (=2048B) foreasier access. Further, packed video packs (V_PCK) and audio packs(A_PCK) are multiplexed into a single stream. All of these areillustrated in FIGS. 13C, 13D, 13E and 13F.

[0121] Further, an MPEG system stream (a general term for the programstream and transport stream) contains time stamps for synchronizedplayback of the multiplexed video and audio streams. The time stamp forthe program stream is PTS (Presentation Time Stamp) which indicates thetime when the frame is to be played. The movie object start timeinformation (M_VOB_V_S_PTM) and the movie object end time information(M_VOB_V_E_PTM) mentioned earlier are time information obtained from thePTS. On the other hand, the time stamp for the transport stream is PCR(Program Clock Reference) which indicates the time of input of data tothe buffer.

[0122] The movie object unit (VOBU) is described below. The movie objectunit (VOBU) is the smallest access unit within the movie object (M_VOB).In order to accomplish highly efficient image compression, the MPEGvideo stream uses not only image compression using spatial frequencycharacteristics within a video frame but also image compression usingmotion characteristics between the frames, i.e. motion characteristicson the time axis. This means that expansion of a video frame requiresinformation on the time axis, i.e. information about a future videoframe or a past vide frame is required, or that the video frame may notbe expanded by itself. In order to solve this problem, in MPEG videostream, a video frame (called I-picture) having no motioncharacteristics on the time axis is inserted every about 0.5 second,achieving higher random accessibility.

[0123] The movie object unit (VOBU) includes some packs from a packcontaining the leading data of an I-picture to a pack immediately beforea pack containing the leading data of the next I-picture. Thus, the Tmap comprises the data size (the number of packs) of each object unit(VOBU) and the playback time (the number of fields) of the video frameswithin the object unit (VOBU).

[0124] For example, an assumption is made that the value of Start in thecell differs from the value of start time information (M_VOB_V_S_PTM) ofthe movie object by one second (60 fields).

[0125] Now, the playback start time of each object unit in the movieobject (M_VOB) can be obtained by accumulating the playback time(length) of each object unit (VOBU) in the T map from the first movieobject. Likewise, the address of each object unit in the movie object(M_VOB) can be obtained by accumulating the data size (the number ofpacks) of each object unit from the first object unit.

[0126] According to the present embodiment, the first three object units(VOBU) of the movie object (M_VOB) have 24, 30 and 24 fieldsrespectively. Thus, from the above calculation method, the video frameafter one second (60 fields) from the top of the movie object (M_VOB) isfound to be included in the third object unit (VOBU#3). Likewise, thestart address of the third object unit (VOBU#3) is found to be the 223rdsector from the head of the object since these object units (VOBU)respectively have data sizes of 125, 98 and 115 sectors.

[0127] Adding the obtained address value to address value for 5010sectors which is the M_VOB start address (ADD_OFF) within the AV fileprovides the start address of the data to be played.

[0128] In the above example, assumption is made that the video framewhich is the 60th field from the top of the movie object (M_VOB) is tobe played. As mentioned earlier however, the MPEG video does not allowdecoding or playback from any one of all video frames. For this reason,the playback starts from the top of the object unit (VOBU) shifted by 6fields away from the 60th field so that the playback starts from theI-picture. It should be noted that a playback can be started exactlyfrom the video field specified by the cell by decoding the above 6fields without displaying.

[0129] The method described above can also provide playback end time ofthe movie object corresponding to the end location in the cellinformation, and the address of the movie object in the AV file.

[0130] Next, the digital broadcasting object information (D_VOBI) willbe described. The digital broadcasting object information is basicallythe same as the movie object information because the digitalbroadcasting object is a subclass derived from the object information. Abig difference, however, is that the movie object (M_VOB) is created byrecording a terrestrial broadcasting. Specifically, while the movieobject is an AV stream encoded by the recorder itself, the digitalbroadcasting object (D_VOB) is not an AV stream encoded by the recorderitself since in the digital broadcasting object data transmitted from adigital broadcast satellite is recorded directly.

[0131] More specifically, when encoding is made by the recorder,internal structure of the stream is clearly known; however, when thedata is a result of direct recording, internal structure is not knownunless the stream is not analyzed, and therefore it is impossible tomake the T map.

[0132] It is possible to analyze the MPEG transport stream suppliedthrough the digital satellite broadcast. In the present embodiment, theT map is created by using information within the MPEG transport streamas to be described here below.

[0133]FIG. 14A shows an MPEG transport stream. FIG. 14B shows anenlarged view of transport packets. FIG. 14C shows PES packets. FIG. 14Dshows a video stream.

[0134] As shown in FIG. 14A, the MPEG transport stream comprises aseries of transport packets. The transport packet includes a header, anadaptation field, and a payload. The adaptation field includes a randomaccess indicator (“random_access_indicator”). The random accessindicator indicates that in this transport packet or the followingtransport packet (more precisely, the transport packet having the sameprogram ID), a next PES packet (i.e. the PES packet in which the firstbyte of the PES packet appears first) contains an access point of thevideo stream or the audio-stream. Particularly, for the video stream,this indicates that the I-picture is included.

[0135] This random access indicator can be used for determining thevideo object unit, and creating the T map.

[0136] The transport packet has a fixed size of 188 bytes. Therefore, aplurality of transport packets (2048 bytes/188 bytes=10 TS packets) arerecorded in one sector of the DVD-RAM comprising 2048 bytes. While it ispossible to handle as 1 pack=1 sector in the movie object (M_VOB), it isimpossible in the digital broadcasting object (D_VOB). Datareading/writing in the DVD-RAM can only be made by the sector. Thereforeeven in the digital broadcasting object, information in the T map ismade up of the playback time length of the movie object unit (VOBU)expressed by the number of video fields, and the data size of the movieobject unit expressed by the number of sectors.

[0137] For the above reason, accuracy of the address is not secured inthe T map when the movie object unit is defined to be from a transportpacket to the next transport packet. Therefore, the movie object unit(VOBU) is defined by using the sector containing the transport packet.

[0138] A PROVIDER_INF field of the digital broadcasting object streaminformation (D_VOB_STI) includes an ID for identifying a broadcastingcompany and particular information related to each broadcasting company.

[0139] Referring now to FIG. 15, description will be made for the audioobject information (AOBI). Again, as a subclass derived from the objectinformation, the audio object information is basically the same as inthe case of the movie object information. A big difference, however, isthat the audio object is an object for the audio system only and is notformatted into the MPEG system stream. More details will be describedhere below.

[0140] Since the audio object is not formatted into the MPEG systemstream, no time stamps are included in the audio object. Therefore,there is no reference time for indicating the playback start time or theplayback end time of the cell or the object. Thus, the audio objectstart time (AOB_A_S_TM) in the audio object general information(AOBI_GI) is entered with 0, whereas the audio object end time(AOB_A_E_TM) is entered with the playback time length. Further, each ofthe Start field and the End field in the cell information is enteredwith relative time within the audio object.

[0141] Another difference of the audio data from the MPEG video data isthat playback of the audio data can be started at any audio frame unit.Therefore, the audio object unit (AOBU) can be defined as the audioframe multiplied by any integer. If the audio object unit is too small,however, a huge amount of data must be handled in the T map. So, theaudio object unit is made to be almost same length of the object unit ofthe movie object, which is about 0.5 second. The T map manages theplayback time length and the data size for each audio object unit.

[0142] Referring now to FIG. 16, description will be made for the stillpicture object information (S_VOBSI). Again, as a subclass derived fromthe object information, the still picture object information (S_VOBSI)is basically the same as in the case of the movie object information. Abig difference, however, is that the still picture object is an objectincluding data of a plurality of sill pictures, and that the stillpicture object is not formatted into the MPEG system stream. Moredetails will be described for the audio object information here below.

[0143] The still picture, differing from the movie or the sound, doesnot have time information. Thus, fields of the starting information andthe ending information in the still picture object general information(S_VOBS_GI) are entered with a number representing the starting stillpicture (Start_Video) and a number representing the last still picture(End_Video) respectively. Further, the Start field and the End field inthe cell are entered with respective picture numbers within the stillpicture object instead of the time information.

[0144] The smallest access unit in still pictures is the frame of stillpicture. Thus, the S map is defined as the access map, which is a tablecontaining the data size (S_VOB_SZ) of each still picture.

[0145] The overall data structure described so far above is shown inFIG. 17. FIG. 17 shows the entirety of the management information in theDVD-RAM. With reference to FIG. 17, all of the management informationwill be described here below. As shown in FIG. 17, the DVD-RAM accordingto the present embodiment is provided with video manager generalinformation (VMGI) 90 and a variety of information tables 92, 94, 96 and98 in addition to the PGC information 50 and 70.

[0146] The VMGI 90 is management information for the whole disc, whichcontains pointer information, i.e. start addresses, of the original PGCinformation 50, the user-defined PGC information 70, and the variety offile management tables 92, 94 . . . . Access to these tables 50, 70, 92,94 . . . becomes possible by referring to the pointer information.

[0147] Now, the file management tables 92, 94, 96 and 98 shown in FIG.17 will be detailed here. Each of these tables 92, 94, 96, 98 is a tablefor managing data files comprising the objects, and is prepared for eachkind of objects. For example, the table 92 is for managing the moviefiles containing movie objects, whereas the table 94 is for managing thestill picture files containing still picture objects.

[0148] As described above, the object information is identified based onthe object ID stored in the cell information in the PGC information.During this operation address of the object information is identifiedvia the file management table 92, 94, 96 or 98. For this purpose, eachof the file management tables 92, 94, 96, 98 contains information aboutthe number of objects under management, ID's of the objects, the size ofeach object information, and so on. For example, when the object IDshows a sequent order, based on this object ID specified by the cellinformation, it is possible to determine an order of the objectspecified by the cell information in the object information managed bythe file management table. Then, from the order of this determinedobject information and the file size, an offset based on the startaddress of the file management table can be calculated to obtain logicaladdress of this determined object information.

[0149] As shown in FIG. 17, the movie file management table 92 is atable for managing movie files containing movie objects. The movie filemanagement table 92 includes the movie object information (M_VOBI) 92 a,92 b, . . . , and the table managing information (M_AVFITI) 92 hcontaining the number of movie object information and the size of themovie objects managed by the table 92. The disc successively recordssame number of movie object information as the number of movie objectinformation contained in the information 92 h. As mentioned earlier, themovie object information 92 a . . . each includes the generalinformation (M_VOB_GI), stream information (M_VOB_STI), and the T map.Further, the T map includes the display time and size (VOBU_ENT) foreach object unit (VOBU).

[0150] The same structure is used in a table (S_AVFIT) 94 for managingstill picture files containing still picture objects, a table (D_AVFIT)96 for managing digital broadcasting files containing digitalbroadcasting objects, and a table (A_AVFIT) 98 for managing audio filescontaining audio objects.

[0151] The original PGC information 50 contains the cell information 61,62, 63 . . . in the order of playback. The cell information containsinformation corresponding to the object information (type and object ID)and the playback section information (Start and End) within the object.The playback section information shown in the cell can be converted toaddress information of the object substance through the access map inthe object information.

[0152] As described earlier, the original PGC information 50 differsfrom the user-defined PGC information 70 only in that the original PGCinformation 50 is automatically generated by the recorder so that all ofthe objects recorded in the disc will be played whereas the user-definedPGC information 70 is information in which the user can freely definethe playback sequence. Thus, the user-defined PGC information 70 has thesame structure with the original PGC information 50.

[0153] By abstracting in advance the information for managing the AVstreams, it becomes possible to define the playback control informationsuch as the PGC information and cell information without depending onthe information peculiar to a given AV stream format, making possible tointegrally manage AV streams. Thus, environment can be realized in whichusers can play AV data without paying attention to the AV format.

[0154] Further by using the above-described data structure, a new AVformat can be easily incorporated into the data structure in DVD-RAM bysimply defining the management information derived from the objectinformation in the same manner as the other existing AV formats.

[0155] (Player Model)

[0156] Referring now to FIG. 18, a player model for playing the aboveoptical disc is described. As shown in FIG. 18, the player comprises apickup 1701, an ECC processor 1702, a track buffer 1703, a PS decoder1705, a TS decoder 1706, an audio decoder 1707, a still picture decoder1708, a switch 1710 and a controller 1711. The optical pickup 1701 readsout data from the optical disc 100. The ECC processor 1702 performserror correction and other operations to the read data. The track buffer1703 tentatively stores the data after the error correction. The PSdecoder 1705 decodes to play program streams such as the movie object(M_VOB). The TS decoder 1706 decodes to play transport streams such asthe digital broadcast object (D_VOB). The audio decoder 1707 decodes toplay the audio object (AOB). The still picture decoder 1708 decodes toplay the still picture object. The switch 1708 switches among thedecoders 1705, 1706 . . . for entry of data. The controller 1711controls each component of the player.

[0157] The data recorded on the optical disc 100 is read by the pickup1701, goes through the ECC processor 1702, and stored in the trackbuffer 1703. The data stored in the track buffer 1703 is then enteredinto one of the decoders 1705, 1706, 1707 and 1708, and then decoded tobe outputted therefrom. In this switching operation, the controller 1711checks the read data and sees the type information of the cellinformation in the PGC information providing the playback sequenceaccording to the method described earlier. The switch 1710 is controlledto switch according to the type information so that the read informationis sent to an appropriate decoder.

[0158] The player of the present embodiment further comprises a digitalinterface 1704 for supplying the AV stream to external equipment.Through this interface with an appropriate communication protocol suchas IEEE1394 and IEC958, the AV stream can be fed to the externalequipment. This is especially advantageous when a program of a new AVformat is outputted through the digital interface 1704 to be played inthe external AV equipment, without using the decoders in this player.

[0159] On the other hand, to support a new AV format in this player, anew decoder 1709 adapting to the new AV format may be coupled to thetrack buffer 1703 in the same way as the other existing decoders1705-1708.

[0160] (Recording Operation by DVD Recorder)

[0161] Next, reference is made to FIG. 19 to describe structure andoperation of a DVD recorder according to the present invention forplaying (reproducing)/recording the above optical disc.

[0162] As shown in the figure, the DVD recorder comprises a userinterface 1901, a system controller 1902, an analog tuner 1903, anencoder 1904, a digital tuner 1905, an analyzer 1906, a displayapparatus 1907, and a decoder 1908. The user interface 1901 provides adisplay for the user and receives requests from the user. The systemcontroller 1902 manages and controls overall of the DVD recorder. Theanalog tuner 1903 receives VHF and UHF waves. The encoder 1904 convertsanalog signals into digital signals to encode the digital signal into anMPEG program stream. The digital tuner 1905 receives satellite digitalbroadcasting. The analyzer 1906 analyzes an MPEG transport stream sentfrom the digital broadcast satellite. The display apparatus 1907includes a TV monitor and speaker system. The decoder 1908 decodes theAV streams. The decoder 1908 includes decoders shown in FIG. 18. The DVDrecorder further comprises a digital interface 1909, a track buffer 1910for temporary storage of the data to be written, and a drive 1911 forwriting data on the DVD-RAM 100. The digital interface 1909 is aninterface for outputting to external equipment through such a protocolas IEEE1394.

[0163] In the DVD recorder having the above configuration, the userinterface portion 1901 first receives demand from the user. The userinterface 1901 transmits a request from the user to the systemcontroller 1902. The system controller 1902 interprets the request intocommands to send to appropriate modules. When the request from the useris to record an analog broadcasting program, the system controller 1902requests the tuner 1903 to receive the program, and the encoder 1904 toencode.

[0164] The encoder 1904 performs video encoding, audio encoding andsystem encoding on the AV data received from the analog tuner 1903 tooutput the encoded data to the track buffer 1910.

[0165] The encoder 1904, upon commencing the encoding operation, sendsthe playback start time (M_VOB_V_S_PTM) of the MPEG program streamencoded to the system controller 1902, and then in parallel with theencoding operation, sends the time length and size information of themovie object unit (VOBU) to the system controller 1902 as sourceinformation for creating the T map.

[0166] Next, the system controller 1902 issues a recording request tothe drive 19111 so that the drive 1911 takes data stored in the trackbuffer 1910 and records this information on the DVD-RAM disc 100. Atthat time, the system controller 1902 instructs the drive 1911 where tostore the information on the disc 100 according to the allocationinformation of the file system.

[0167] Ending of the recording operation is demanded by the user througha stop request. The stop request from the user is transmitted throughthe user interface 1901 to the system controller 1902. The systemcontroller 1902 then issues the stop request to the analog tuner 1903and the encoder 1904.

[0168] Upon reception of the stop request from the system controller1902, the encoder stops the encoding operation, and sends the playbackstop time (M_VOB_V_E_PTM) of the last encoded MPEG program stream to thesystem controller 1902.

[0169] After the encoding operation is over, the system controller 1902creates the movie object information (M_VOBI) based on the informationreceived from the encoder 1904. Next, the system controller 1902 createsthe cell information corresponding to the movie objet information(M_VOBI). The important point here is that the type information in thecell information must be specified as “M_VOB”. As described earlier, theinformation in the cell information is configured without depending onthe movie object (M_VOB), and all information which depends on the movieobject (M_VOB) is concealed into the movie object information (M_VOBI).Therefore, an error in recognizing the type information in the cellinformation will lead to inability to perform normal playback, possiblyresulting in system down.

[0170] Finally, the system controller 1902 requests the drive 1911 tofinish recording the data stored in the track buffer 1910, and to recordthe movie object information (M_VOBI) and cell information. The drive1911 records the data remaining in the track buffer 1910, the movieobject information (M_VOBI) and the cell information on the DVD-RAM,subsequently completing the recording operation.

[0171] Next, description will be made in a case of the user's requestfor recording a digital broadcast program.

[0172] The user's request for recording the digital broadcasting programis transmitted through the user interface 1901 to the system controller1902. The system controller 1902 then requests the digital tuner 1905 torecord, and the analyzer 1906 to analyze received data.

[0173] An MPEG transport stream sent from the digital tuner 1905 is sentthrough the analyzer 1906 to the track buffer 1910. The analyzer 1906first picks up from the MPEG transport stream the start time information(D_VOB_V_S_PTM) as information necessary for generating the digitalbroadcasting object information (D_VOBI), and sends this information tothe system controller 1902. Next, the analyzer 1906 determines the movieobject unit (VOBU) in the MPEG transport stream, and sends the timelength and size of the movie object unit as information necessary forcreating the T map to the system controller 1902. It should be notedthat the movie object unit (VOBU) can be determined, as describedearlier, based on the random access indicator (random_access_indicator)in the application field contained in the TS packet header.

[0174] Next, the system controller 1902 outputs a recording request tothe drive 1911. Then the drive 1911 picks up the data stored in thetrack buffer 1910 and records the data in the DVD-RAM disc 100. At thistime, the system controller 1902 also informs the drive 1911 where thedrive 1911 should record the information on the disc 100, based onallocation information of the file system.

[0175] Ending of the recording operation is instructed by the userthrough a stop request. The stop request from the user is transmittedthrough the user interface 1901 to the system controllers 1902. Thesystem controller 1902 then issues the stop request to the digital tuner1905 and the analyzer 1906.

[0176] The analyzer 1906, upon reception of the stop request from thesystem controller 1902, stops the analyzing operation, and sends thedisplay end time (D_VOB_V_E_PTM) of the movie object unit (VOBU) of thelast analyzed MPEG transport stream to the system controller 1902.

[0177] After the completion of receiving the digital broadcasting, thesystem controller 1902 creates the digital broadcasting objectinformation (D_VOBI) based on the information received from the analyzer1906, and next, creates the cell information corresponding to thedigital broadcasting objet information (D_VOBI), at which time the typeinformation in the cell information is specified as “D_VOB”.

[0178] Finally, the system controller 1902 requests the drive 1911 tofinish recording the data stored in the track buffer 1910, and to recordthe digital broadcasting object information and cell information. Thedrive 1911 records the data remaining in the track buffer 1910, thedigital broadcasting object information (D_VOBI) and the cellinformation on the DVD-RAM disc 100, completing the recording operation.

[0179] The above description is made on the basis that the user makesrequest to start and stop recording. When a timer recording functioncommonly provided in a VTR system is used, the system controllerautomatically issues recording start and stop commands in stead ofuser's request, and thus the steps of operation performed by the DVDrecorder are essentially the same.

[0180] (Playback Operation by DVD Recorder)

[0181] Next, playback operation in the DVD recorder will be described.

[0182] First, the user interface 1901 receives a request from the user.The user interface 1901 transmits the request to the system controller1902. The system controller 1902 interprets the user's request tocommands to send them to appropriate modules. For example, when theuse's request demands playback of a PGC information, the systemcontroller 1902 analyzes the PGC information and cell information to seewhich object should be played. Description will be made below for a casein which an original PGC comprising one movie object (M_VOB) and onecell information is played.

[0183] The system controller 1902 first analyzes the type informationstored in the cell information in the PGC information. When the typeinformation is “M_VOB”, it means that the AV stream to be played is thestream recorded as the MPEG program stream. Next, the system controller1902 refers to the ID of the cell information to find the correspondingmovie object information (M_VOBI) from the table (M_AVFIT). The systemcontroller 1902 then finds start address and end address of the AV datato be played according to the start time information (M_VOB_V_S_PTM) andend time information (M_VOB_V_E_PTM) contained in the movie objectinformation, and T map.

[0184] Next, the system controller 1902 sends to the drive 1911 arequest for reading from DVD-RAM 100, together with the start address ofthe reading. The drive 1911 then reads out AV data from the addressgiven by the system controller 1902, and stores the read data to thetrack buffer 1910.

[0185] Next, the system controller 1902 sends to the decoder 1908 adecoding request of the MPEG program stream. The decoder 1908 then readout the AV data stored in the track buffer 1910 to decode the read data.The decoded AV data is outputted through the display apparatus 1907.

[0186] On the completion of reading all the data instructed by thesystem controller 1902, the drive 1911 reports to the system controller1902 that the reading operation is completed. The system controller 1902then issues a command to the decoder 1908 to stop the playbackoperation. The decoder 1908 continues to decode data until the trackbuffer 1910 is emptied. After all the data is decoded and played, thedecoder 1908 reports to the system controller 1902 that the replayoperation is finished, then bringing the playback operation to acomplete end.

[0187] The above description was made for the case in which one originalPGC containing one movie object (M_VOB) and one cell information is tobe played. However, the playback operation of the AV stream can beperformed by the same steps of operation whether the original PGCcontains only one digital broadcasting object (D_VOB), contains aplurality of movie objects, contains a plurality of digital broadcastingobjects, or contains both movie objects and digital broadcasting object.Further, the same goes with a case in which the original PGC contains aplurality of cells, or in a case of the user-defined PGC.

[0188] Further, the audio object (AOB) and other AV stream, i.e. thestill picture object (S_VOBS) are handled essentially in the sameprocedures by the same modules, differing only in the configurationwithin the decoder 1908. In these cases, the decoder 1908 may beconfigured by the PS decoder 1705, the TS decoder 1706, the audiodecoder 1707, or the still picture decoder 1708 as shown in FIG. 18.

[0189] Next, an example is taken for a case in which the decoder 1908does not have capabilities for playing all kinds of the AV streams.

[0190] If the decoder 1908 does not have playback capability for theMPEG transport stream, playback operation by the decoder 1908 isimpossible as described above. In such a case the digital interfaceportion 1909 is used to supply external equipment with the data, so thatthe data can be played by the external equipment.

[0191] When the system controller 1902 finds from the cell informationin the PGC information that the user requests playback of a digitalbroadcasting object (D_VOB) not supported by the system, the systemcontroller 1902 requests the digital interface 1909 for external outputinstead of requesting the decoder 1908 for playback. The digitalinterface 1909 transmits AV data stored in the track buffer 1910 inaccordance with the communication protocol of the connected digitalinterface. Other operations performed are the same as those performedwhen the movie object (M_VOB) is played.

[0192] A judgment must be made whether or not the decoder 1908 iscompatible with the AV stream requested for replay. This judgment may bemade by the system controller 1902 by itself, or the system controller1902 may ask the decoder 1908.

[0193] (DVD Player)

[0194] Next, with reference to FIG. 20, a DVD player according to thepresent invention is described. The DVD player is a realization of theplayer model described above to play the above optical disc.

[0195] As shown in the figure, the DVD player comprises a user interface2001, a system controller 2002, a display apparatus 2003, a decoder2004, a digital interface 2005, a track buffer 2006 and a drive 2007.The user interface 2001 receives requests from the user and displayssome indications to the user. The system controller 2002 manages andcontrols overall of the DVD player. The display apparatus 2003 includesa TV monitor and speaker system. The decoder 2004 decodes the MPEGstream. The digital interface 2005 connects to IEEE1394 and so on. Thetrack buffer 2006 temporally stores the data read from the DVD-RAM 100.The drive 2007 reads data out from the DVD-RAM 100. The DVD playerconfigured as above performs the same playback operations as in the DVDrecorder described earlier.

[0196] It should be noted that the DVD-RAM is taken as an example in thepresent embodiment. However, the same description so far has been madeapplies to other media. The present invention should not be limited tosuch media as the DVD-RAM and other optical discs.

[0197] Further, according to the present embodiment, the AV stream notsupported by the decoder is played through the digital interface.However, those AV streams which are supported by the decoder may beoutputted to external equipment through the digital interface dependingon the request from the user.

[0198] Further, according to the present embodiment, the audio data andthe still picture data were treated as unique data differing from theMPEG streams. However, these data may also be recorded in the format ofMPEG system stream.

[0199] Although the present invention has been described in connectionwith specified embodiments thereof, many other modifications,corrections and applications are apparent to those skilled in the art.Therefore, the present invention is not limited by the disclosureprovided herein but limited only to the scope of the appended claims.

What is claimed is:
 1. An information recording medium for recording of objects which include at least one of image data and audio data, the medium comprising: object information including identification information and map information for each object, the identification information identifying the object, the map information associating a playback time of the object with an address of a component of the object on the medium, the component being played back at the playback time; and playback control information including at least one of cell information in a predetermined order, said cell information containing type information, identification information and playback section information, the type information indicating a kind of the object, the identification information identifying the object, the playback section information specifying a section in which the object is being played; wherein the order of cell information in the playback control information indicates the order in which the objects specified by respective cell information are played.
 2. The information recording medium according to claim 1, wherein the order of cell information is determined according to the order in which the objects specified in respective cell information are recorded to the medium.
 3. The information recording medium according to claim 1, wherein the object information further includes time at which the object starts to be played, and time at which the object ends to be played.
 4. The information recording medium according to claim 1, wherein the map information includes a start address of the object information, data size of the object, and playback time length of the components of the object.
 5. The information recording medium according to claim 1, further comprising a management table for managing the object information by a kind of object, the management table including a start address of the management table, the number of managed object information, and the size of the managed object information.
 6. The information recording medium according to claim 1, wherein the kind of object includes at least one of movie data, still picture data, digital broadcast data, and audio data.
 7. An apparatus for recording data to the information recording medium according to claim 1, comprising: a first unit for receiving an MPEG transport stream from external equipment; a second unit for reading the “random_access_indicator” from the received MPEG transport stream, and generating an access point information based on the read “random_access_indicator”.
 8. The apparatus for recording data according to claim 7, wherein the access point information includes the time length and the size of the component of the object.
 9. The apparatus for recording data according to claim 7, wherein the second unit generates the time at which the object starts to be played and the time at which the object ends to be played, by analyzing MPEG transport stream.
 10. The apparatus for recording data according to claim 7, further comprising: an unit for receiving the signal of an analog broadcasting; and an encoder for converting the received signal into digital signal to encode the digital signal to MPEG program stream.
 11. An apparatus for recording data to the information recording medium according to claim 1, comprising a unit for recording type information into the playback control information, and the type information for indicating a kind of object.
 12. An apparatus for reproducing data from the information recording medium according to claim 1, comprising: a pickup unit for reading object data recorded in the recording medium; a plurality of decoding units for decoding the read object data according to the kind of the object; a selecting unit for selecting one of the decoding units for playback operation; and a controlling unit for reading the type information included in the playback control information, and controlling the selecting units to select one of the decoding units according to the read type information.
 13. The apparatus according to claim 12, further comprising: an external interface for passing object data read out from the recording medium to external equipment; the selecting unit for selecting one of the plurality of decoding units and the external interface; and the controlling unit for controlling the selecting unit so as to select the external interface when the kind of the object specified by the playback control information is a kind of an object which can not be decoded by the decoding units.
 14. A method for recording data to the information recording medium according to claim 1, comprising the steps of: receiving an MPEG transport stream from external equipment; reading the “random_access_indicator” from the received MPEG transport stream; and generating an access point information based on the read “random_access indicator”.
 15. A method for reproducing data from the information recording medium according to claim 1, comprising the steps of: reading out object data from the recording medium; reading out the type information of the playback control information in the recording medium; and decoding the read object data according to the read type information.
 16. The method according to claim 15 further comprising the step of passing the read object data to external equipment without decoding when the kind of the object specified by the playback control information is a kind of an object which can not be decoded. 